The present invention relates to a layered structure comprising at least two material layers, a sensor, a method for producing layered structure and its use.
Conductive polymers are materials which have been made conductive by doping with suitable substance. In the doping process both electron acceptors and donors react with polymer structure resulting in highly conducting derivatives. These reactions are called ‘doping’ in analogy to semiconductors, though they are closer to solid-state chemical reactions. Another method for generating electrical conductivity in polymers is blending in which conductive polymer and insulating material are mixed. Electrical properties of conductive polymers can be changed over the fall range of conductivity from insulators to metallic conductors. An example of a conductive polymer is polyaniline which is a synthetic organic polymer obtained by the chemical or electrochemical oxidative polymerization of aniline. Emeraldine base, which is the most stable insulating form of polyaniline, can be made conducting either by oxidation or by expose of functional protonic acids e.g. HCl or H2SO4. Correspondingly, the conducting emeraldine can be made less conducting or even insulating by a dedoping reaction caused by a reduction process or by exposure to alkaline materials. There are wide prospects of using conductive polymers in variety of consumer products. Examples of known use of conductive polymers are batteries, electrical circuits, capacitors, EMI shields, organic LEDs, corrosion prevention products and antistatic products for use in e.g. package industry, construction, clothes, automotive industry, mining.
Conductive polymers, materials and products are known in the art from many patent publications of which some of them are disclosed in the following.
U.S. Pat. No. 5,783,111 discloses compositions comprising electrically conducting polyaniline and particular substituted aromatic compounds that simultaneously form hydrogen bonds and ring-ring interactions with, respectively, the NH-groups and the six-membered rings of the conducting polyanilines. The conducting polyaniline compositions show drastically enhanced processibility and their blends with insulating or semiconducting materials exhibit significantly improved electrical properties.
U.S. Pat. No. 5,656,081 discloses a press for printing an electrical circuit component directly on a substrate with an electrically conductive liquid. A method of making such a press includes the steps of providing a press surface and engraving the press surface with the plurality of liquid carrying cells which are in liquid communication with each other in both the printing direction and in the transverse direction.
U.S. Pat. No. 5,622,652 discloses electrically conductive liquid for directly printing an electrical circuit component onto a substrate and a method for making such a liquid. The invention relates to an electrically conductive liquid which, when printed onto a substrate is capable of carrying out an electrical circuit function. Using the method there is no need for post-printing steps such as metal etching, catalytic ink activation or electroless deposition.